NAB and SAB naval bronze fasteners
Woodstock supplies made-to-order fasteners in nickel aluminium bronze (NAB) and aluminium silicon bronze (SAB) for defence and marine procurement.
This page is a summary. The detail is on our dedicated site, nab-sab-fasteners.co.uk.
DEF STAN 02-833 Part 2 — Nickel Aluminium Bronze; predecessor NES 833
CW307G is CuAl10Ni5Fe4 in BS EN 12163; BS 2874 CA104 is the legacy cross-reference. DEF STAN 02-833 names CW307G as the nearest commercial EN designation, but it is not a close match: the cross-reference is not an equivalence.
The naval material standard is DEF STAN 02-833 Part 2 (Issue 4, 28 September 2018), a Category 1 maritime Defence Standard covering NAB forgings, forging stock, rods and sections. It followed NES 833. A drawing that cites NES 833 is reviewed against that document rather than assumed identical to the later Def Stan.
DEF STAN 02-833 sets its own chemistry, testing and heat-treatment requirements beyond BS EN 12163: nickel must exceed iron, Izod impact testing applies by ruling section, and heat treatment is mandatory for extruded rods and sections up to 40 mm and rolled and forged rods and sections up to 30 mm, advisory above those sizes.
NAB offers excellent resistance to seawater corrosion, erosion and cavitation when the alloy, microstructure and manufacturing condition are correctly controlled.
Relative magnetic permeability is typically around 1.4–1.5, so NAB is not a low-signature material; SAB is specified where a permeability limit applies.
C63000 and C63200 (ASTM B150) are comparable US wrought grades but are not specification-equivalent to CW307G. C95800 (ASTM B148) is a cast grade, not a wrought fastener material.
NAB material data and DEF STAN 02-833 detail →
DEF STAN 02-879 Part 2 Annex D — Aluminium Silicon Bronze; predecessors DEF STAN 02-834 Part 2 and NES 834
SAB — aluminium silicon bronze — is CuAl6Si2Fe, designated CW301G, with CA107 as the legacy cross-reference.
The naval material requirement is DEF STAN 02-879 Part 2 Annex D (Issue 3, 28 September 2018). It superseded DEF STAN 02-834 Part 2 in September 2011, which in turn followed NES 834.
SAB is specified where controlled low magnetic permeability is required: relative permeability is not to exceed 1.05, batch-tested. Tighter limits are a drawing or contract requirement and are handled at enquiry stage.
Stress corrosion — read before specifying. DEF STAN 02-879 Part 2 records that aluminium silicon bronze fasteners have suffered rapid stress corrosion cracking in moist marine atmospheres when tightened beyond their proof stress (clause 11.6), and notes that the alloy is no longer favoured for general corrosion-resistant fastener use for that reason (Annex A). SAB is specified where controlled low magnetic permeability is required.
DEF STAN 02-862 Part 2 — naval fastener manufacturing and certification route
DEF STAN 02-833 Part 2 and DEF STAN 02-879 Part 2 Annex D are the relevant material standards; DEF STAN 02-862 Part 2 is the naval fastener manufacturing and certification route.
It is not a material specification and it is not "the heat treatment". For NAB and SAB, DEF STAN 02-862 Part 2 requires machined threads and prohibits cold-forming of bolt heads, screw heads and nuts; its permitted routes include machining from bar and, for bolt or screw heads, hot heading. Marking and certification requirements are also specified. The NAB material heat treatment is a requirement of DEF STAN 02-833 Part 2, as set out above.
Fasteners are supplied to the DEF STAN 02-862 Part 2 route where specified.
Standard status
Standard status. DEF STAN 02-862 Parts 1–3 Issue 3 (14 August 2011) were withdrawn in March 2023; no replacement was issued and no reason was recorded. DEF STAN 02-833 Part 2 Issue 4 (28 September 2018) was archived in May 2025 under the JSP 920 Beyond Review Date programme; DEF STAN 02-879 Part 2 Issue 3 (28 September 2018) was archived in May 2025 under JSP 920. DEF STAN 02-834 Part 2 Issue 1 was withdrawn in September 2011 and replaced by DEF STAN 02-879 Part 2 Issue 1. DStan has confirmed that archived and withdrawn Defence Standards may continue to be used where the full implications of selection have been considered and identified risks and mitigation actions are recorded in a risk register, for example a project SMP. For this purpose, Beyond Review Date and Withdrawn are treated as Archived.
Status confirmed with UK Defence Standardization, 17 September 2026.
Standards detail on nab-sab-fasteners.co.uk →
How NAB and SAB fasteners are supplied
- Made to order.
- EN 10204 3.1 material certificates available when specified at the time of enquiry.
- Quotes within one working day.
Product range
Hex Head Bolts and Hex Head Setscrews · hex nuts · washers · studs · socket screws · slotted machine screws · UNC / UNF imperial · made to drawing
What is the difference between NAB and SAB fasteners?
NAB is nickel aluminium bronze, covered for naval use by DEF STAN 02-833 Part 2; its relative magnetic permeability is typically around 1.4–1.5. SAB is aluminium silicon bronze (CW301G), specified where controlled low magnetic permeability is required — not to exceed 1.05, batch-tested.
Can archived or withdrawn Defence Standards still be used?
DStan has confirmed that archived and withdrawn Defence Standards may continue to be used where the full implications of selection have been considered and identified risks and mitigation actions are recorded in a risk register, for example a project SMP.
My drawing calls up DEF STAN 02-834 or NES 834. Which document applies?
DEF STAN 02-879 Part 2 superseded DEF STAN 02-834 Part 2 in September 2011. NES 833 and NES 834 are predecessor documents and are not assumed identical to the later Defence Standards.
Can C95800 or C63000 be used instead of DEF STAN 02-833 NAB?
C63000 and C63200 are comparable US wrought grades but are not specification-equivalent to CW307G. C95800 is a cast grade rather than a wrought fastener material; substitution of C95800 needs customer or design-authority approval.